1. Field of the Invention
The present invention relates to an electret device and an electrostatic operating apparatus, and more particularly, it relates to an electret device comprising an electret film formed on a main surface of a substrate and an electrostatic operating apparatus comprising the electret device.
2. Description of the Background Art
An electret device comprising an electret film formed on a main surface of a substrate is known in general. As the conventional electret device, an electret device with an electret film flatly formed on a main surface of a flat substrate is disclosed. In this conventional electret device, charges are injected into a flat silicon oxide film by thermal oxidation, thereby forming the flat electret film.